The present invention relates to an antifouling structure and method effective to inhibit deposition of oceanic organisms such as barnacles, blue mussels, and seaweed, hereinafter referred to as an organism deposit-inhibition structure.
Offshore or marine structures in contact with seawater are always exposed to contamination by oceanic organisms, resulting in damage to appearance or malfunction. For instance, ships suffer a driving force drop when many forms of oceanic organisms are deposited onto their bottoms, etc., and thermoelectric power plants are forced to stop operation when various forms of oceanic organisms are built up on their seawater intake pits, because a serious problem arises in connection with the circulation of a seawater serving as a cooling medium.
Among scores of techniques for inhibiting marine deposits studied so far in the art, there is typically now available a method for protecting an offshore structure against contamination, in which the surface of that structure in contact with seawater is coated with a coating material containing cuprous oxide or organotin.
Another method is disclosed in JP-A-60-209505 that is directed to an adhesive member for inhibiting oceanic deposits, which comprises a sheet of copper or a copper alloy, a primer layer provided on one surface thereof, and an adhesive material layer formed on the primer layer.
A grave problem with the method using a coating material, however, is that the coating material has a service life of as short as one year, since even when applied in a thick layer, it is likely to peel away. Accordingly, there is needed troublesome maintenance work in which the coating material must be renewed each year.
The oceanic organism deposit-inhibiting member disclosed in JP-A-60-209505, on the other hand, is found to be less than satisfactory in terms of corrosion resistance and antifouling effect, because of the use of a copper or a copper-nickel (Cu--Ni) alloy.
Our years of study have now revealed that the application of a beryllium-copper alloy to an offshore structure achieves a much-more excellent antifouling effect. The reason would be that beryllium and copper ions interact synergistically, producing a great effect on inhibiting oceanic organisms from having access to the offshore structure and preventing their propagation. In other words, we have now found that the beryllium-copper alloy has a combined effect both on inhibiting marine deposits and on the continued liberation of copper ions.
A main object of the invention is to provide a method for making an organism deposit-inhibiting pipe, which can be easily produced, excels in the capability to inhibit deposition of organisms and durability, dispenses with maintenance work, and offers no toxicity problem.